The present invention relates to local area networks and more particularly to a local area network organized around a fiber optic active star node.
A local area network (LAN) for use in emergency command center communications should satisfy requirements for portability, flexibility and expandability. The portability requirement suggests that the LAN be lightweight, self-contained and rapidly deployable. In certain emergency situations, the command center may have to be relocated. In this case, the LAN must be retrieved, packed in a truck or helicopter for transport to the new site, and there rapidly deployed. The light weight and small size of fiber optics meet this portability requirement. In addition, a fiber optic medium offers well known benefits of immunity to electrical interference and lightning strikes, elimination of ground loops, and no catastrophic shorting in the event of a damaged cable section.
The requirement of LAN flexibility refers to the network's capability to support a wide variety of terminal devices for data services. Such flexibility may be provided by the utilization of standard electrical data interface units. In addition to data transmission, the distribution of one or more video channels is also desired for the transmission of images or maps to monitor the status of the emergency situation.
The requirement for expandability relates to the size of the LAN as measured by the number of terminal devices that may be interconnected by the network. The network must be balanced and should operate with various deployments ranging from a few to many subscriber stations. Furthermore, growth in the number of network subscribers should be modular. A dynamic reconfiguration to add additional subscribers to an operating network should not interfere with the communications between active terminals originally connected to the LAN.
It is therefore an object of the present invention to provide a local area network which is light in weight for portability.
Another object of the invention is a local area network capable of supporting a wide variety of terminal devices for data services.
Still another object of the invention is such a local area network which is expandable in a modular fashion to permit the interconnection of numerous terminal users.